Switch-incorporating plug socket

ABSTRACT

The switch-incorporating plug socket according to the invention comprises a socket having an interlocking switch provided in a closed compartment thereof, a plug adapted to be inserted into said socket and a union joint for intercoupling said socket and said plug, and is so designed that it establish an electrical connection between an electric equipment connected thereto and a power source only when the union joint is screwed in the intercoupling direction after the plug is inserted into the socket, so that outward discharge otherwise occurring at the engagement or disengagement of the plug socket is prevented and the power can be supplied safely even at a location where there is the danger of explosion.

United States Patent 1191 Mori et al.

SWITCH-INCORPORATING PLUG SOCKET lnventors: Shiniiro Mori, Tokyo; Akitoshi Takada, Yokohama, both of Japan Assignee: Mori Denki Manufacturing Co.,

Ltd., Tokyo, Japan Filed: Sept. 24, 1973 Appl. 190.; 400,119

Foreign Application Priority Data May 23, 1973 Japan 48-56706 U.S. Cl. ZOO/51.09 Int. Cl H01! 33/30 Field of Search ZOO/51.07, 51.08, 51.09,

References Cited UNITED STATES PATENTS 8/1934 Reynolds et al. ZOO/51.09 6/1969 Fee ZOO/51.09

3,596,019 9/1969 Koester 200/5109 Primary Examiner-David Smith, Jr. Attorney, Agent, or FirmWenderoth, Lind & Ponack 5 7] ABSTRACT The switch-incorporating plug socket according to the invention comprises a socket having an interlocking switch provided in a closed compartment thereof, a plug adapted to be inserted into said socket and a union joint for intercoupling said socket and said plug, and is so designed that it establish an electrical connection between an electric equipment connected thereto and a power source only when the union joint is screwed in 'the intercoupling direction after the plug is inserted into the socket, so that outward discharge otherwise occurring at the engagement or disengagement of the plug socket is prevented and the power can be supplied safely even at a location where there is the danger of explosion.

2 Claims, 6 Drawing Figures gym 4 1 SWITCH-INCORPORATING PLUG SOCKET BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a switch-incorporating plug socket so designed that outward discharge occurring at the engagement or disengagement of the plug socket is prevented and the engagement or disengagement of the plug socket can be effected under no voltage.

2. Description of the Prior Art When a hand lamp or portable electric equipment is used in a plant or other locations where there is the danger of explosion, an enclosed type plug socket or explosion-proof type plug socket is usually used for supplying power to the electric equipment therethrough. The conventionally used enclosed type, switchincorporated plug and socket has an interlocking switch provided therein and is so designed that the switch is actuated to supply a current to the associated electric equipment when a union joint is screwed in a direction to intercouple the plug and socket after the plug is inserted into the socket, whereby outward discharge otherwise occurring at the engagement or disengagement of the plug and socket is prevented. The engagement or disengagement of the plug is possible under no voltage, so that accidents arising from electric shock can be prevented and power supply can be achieved safely.

As stated, this type of plug socket has been known. However, the conventional plug sockets, because of the complicated mechanism at the switch portion, unexceptionally have required much time and labor for manufacture and assembly and particularly the assembly thereof has required skill, making it impossible to provide them at low costs.

SUMMARY OF THE INVENTION The present invention consists in an enclosed type, switch-incorporated plug socket which is provided therein an interlocking switch and designed such that the switch is actuated to conduct a current when a union joint is screwed in a direction to intercouple the plug and socket after the plug is inserted into the socket, and the object of the invention is to provide a switch-incorporated plug socket of the type described in which improvements are made in the switch portion and which is simple in construction as a whole, easy to manufacture and assemble, and inexpensive and economical.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the whole switchincorporated plug socket of the present invention as assembled;

FIG. 2 is a perspective view showing explicitly the component parts of the plug socket shown in FIG. 1;

FIG. 3 is a plan view of the entire switchincorporated plug socket of the invention as assembled;

FIG. 4 is a sectional view of the switch-incorporated plug socket of the invention, with the plug and the socket being disengaged;

FIG. 5 is a sectional view of the switch-incorporated plug socket of the invention, with the plug being inserted into the socket; and

FIG. 6 is a perspective view showing the manner in which the switch-incorporated plug socket of the invention is actually used.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 6 is illustrated the manner in which the switch-incorporated plug socket of the invention is actually used.

As shown, cords 2 are inserted from both sides into a bottomed box 1 which can be fixed to a wall surface or post and on which the switch-incorporated plug socket of the invention is mounted. The plug socket of the invention comprises a plug 4 and a socket 3 and and establishes an electrical connection between an electric equipment (not shown) connected to the plug 4 by a cord 5 and a power source to supply a current from said power source to said electric equipment when the plug 4 is inserted into the socket 3.

Now, the construction of the switch-incorporated plug socket of the invention will be described in detail with reference to FIGS. 1 to 5.

A main body 10 of the socket is provided with a flange 11 by which the socket is fixed to the box 1 and with a tapped sleeve 12 on one side of said flange. A mount 13 made of an electrically insulating material is fixed to the flange 11 by means of screws 14, 14 on the side opposite to the tapped sleeve 12. A cavity 15 is formed in a portion of the mount 13 extending into the tapped sleeve, said cavity being open in the same direction as the direction in which said tapped sleeve is open. Two cylindrical plug receiving members 16, 16 are connected to the underside of the mount 13 within the cavity 15 by means of bolts 17, 17 said plug receiving members being open in the same direction as the direction in which said tapped sleeve is open.

Metal strips 18, 18 are fixed to the surface of the mount 13 opposite to the cavity 15 by means of the bolts 17, 17 by which the plug receiving members are secured. Thus, the metal strips 18 and the plug receiving members 16 are electrically connected with each other. Terminal plates 19, 19 are also fixed to the mount 13 at positions opposite to the metal strips 18, 18 respectively, with their cord connecting portions 20, 20 projecting outwardly from the mount 13.

A guide rod 21 is slidably extended through the center of the mount 13 in parallel to the plug receiving members 16, 16 with end thereof projecting into the cavity 15. This guide rod 21 has a large diameter portion 22 projecting above the mount 13 and is provided with an annular groove 23 perpendicular to the axis of the large diameter portion.

Side plates 24, 24 extending parallel to the plug receiving members are fixed to the opposite side walls of the mount 13 parallel to the sets of the metal strip 18 and terminal plate 19 respectively at portions thereof, with the other portions projecting above the mount 13. The side plates 24, 24 respectively are formed with openings 25, 25 and a pressing plate 26 of an electrically insulating material is disposed horizontally with the opposite ends thereof respectively received in the openings 25, 25 of said two opposed side plates. The pressing plate 26 is formed with a longitudinally elongate large opening 27 at the central portion and transverse grooves 28, 28 at the opposite end portions thereof. The pressing plate 26 has connected to the underside thereof facing the mount 13 contactor strips 29, 29 each of which is adapted to be brought into contact concurrently with the metal strip 18 and terminal plate 19. In mounting the pressing plate 26, the small diameter upper portion of the guide rod 21 is extended in the opening 27 of said pressing plate and its top end is loosely received in a hole formed in a bracket 31 which .is fixed to the mount 13, and a spring 30 is mounted around the small diameter portion of said guide rod, whereby said guide rod is constantly urged towards the tapped sleeve.

Leaf springs 32, 32 respectively have one ends anchored in the grooves 28, 28 of the pressing plate 26 and the other ends in the annular groove 23 of the guide rod 21. These leaf springs serve to move the pressing plate away from the mount when the guide rod 21 is pushed towards the tapped sleeve, and to move the same towards the mount when the guide rod is pushed in the opposite direction.

In the use of the socket of the construction described above, cords (not shown) are connected to the terminal plates 19, 19 on the mount 13 respectively. For preventing troubles arising from electrical shorting between the cords and the switch portion and protecting the switch portion against dusts, the socket is convered by a transparent cover 33, with the cord connecting portions of the terminal plates only protruding outwardly from said cover.

Next, the construction of the plug which will be used in combination with the above-described socket will be described. A main body 34 of the plug is made of an electrically insulating material and provided with slots 35, 35 for receiving the plug receiving members 16, 16, said slots being open in the plug inserting direction. Terminals 37, 37 are provided on the main body 34 at locations opposite to the openings of the slots. A plug cover 38 is connected to the main body 34 of the plug and a plug union 39 is mounted around said plug cover 38 for meshing engagement with the tapped sleeve 12.

The socket 3 is fixed to the box 1 as shown in FIG. 6 and the plug socket becomes conductive when the plug 4 is inserted into the socket 3.

In connecting the plug with the socket, the main body 34 of the plug is inserted into the tapped sleeve 12 of the main body of the socket, with the plug receiving members 16, 16 of said socket respectively received in the slots 35, 35 of the plug, whereby plugs 36, 36 provided in said slots are respectively received in said plug receiving members 16, 16. At this point, no currect passes in the plug socket since the metal strips 18, 18 integral with the respective plug receiving members are not connected with the terminal plates 19, 19. After the main body of the plug has been inserted into the tapped sleeve 12 of the socket, the plug union 39 is rotated in the intercoupling direction, whereby the main body of the plugmoves into the socket and pushes the guide rod 21 by the end wall of the main body of the plug where the slots are formed, so that said guide rod 21 moves in the opposite direction to the tapped sleeve 12 against the spring 30.

The leaf springs 32, 32 hold the pressing plate 26 away from the mount 13 while the guide rod 21 is being urged towards the tapped sleeve 12, but cause it to move towards the mount 13 when the guide rod 21 is moved in the opposite direction to the tapped sleeve.

Therefore, when the plug union 39 is completely screwed and the guide rod 21 is moved by the main body 34 of the plug, the pressing plate 26 is moved towards the mount 13 by the action of the leaf springs 32, 32. Thus, the metal strips 18 and the terminal plates 19 are electrically connected by the contactor plates 29, 29 carried on said pressing plate, and the plug and sockets are electrically connected to supply a current therethrough.

For withdrawing the plug, the plug union 39 is rotated in the opposite direction to the case described above and the plug main body is pulled off the socket, whereupon the guide rod 21 is moved towards the tapped sleeve 12 by the spring 30, so that the pressing plate 26 is moved away from the mount 13 and the electrical connection between the metal strips 18 and the terminal plates 19 is severed.

As may be understood from the foregoing description, the plug socket of the present invention is simplified in the construction of the switch portion as compared with the conventional enclosed type plug socket and therefore, can be manufactured and assembled easily and provided at a low cost.

We claim:

1. A switch-incorporated plug socket comprising a socket having a main body provided with a tapped sleeve, a mount of electrically insulating material fixed to the main body on the opposite side to said tapped sleeve, a plurality of plug receiving members fixed to one end of said mount within said tapped sleeve and respectively opening in the same direction as the direction in which said tapped sleeve is open, rnetalstrips fixed on said mount and electrically connected with said plug receiving members respectively, terminal plates fixed on said mount at locations opposite to said metal strips respectively, a guide rod slidably extending through the center of said mount in parallel to the plug receiving members with one end thereof protruding into said tapped sleeve, said guide rod being enlarged in diameter at the central portion thereof and formed with an annular groove at said enlarged diameter portion perpendicular to the axis thereof, side plates fixed in opposed relation to the opposite side walls of said mount parallel to said metal strips and terminal plates with portions thereof projecting above said mount, a pressing plate of electrically insulating material disposed horizontally with the opposite ends thereof re spectively received in openings formed in said side plates, said pressing plate being provided at the central portion with an opening in which said guide rod is extended, contactor strips fixed to the opposite end portions of said pressing plate and adapted to be brought into contact concurrently with said metal strips and terminal plates, means for urging said guide rod constantly towards the tapped sleeve, and leaf springs mounted between the opposite end portions of the pressing plate and the annular groove of the guide rod and adapted to move the pressing plate away from the mount when the guide rod is moved towards the tapped sleeve and to move the same towards the mount when the guide rod is moved in the opposite direction to the tapped sleeve; and a plug having a main body adapted to be inserted into the tapped sleeve of said socket, plugs provided on the main body and adapted to be received in the plug receiving members of said socket respectively, terminals provided on the main body on the opposite side to said plugs and electrically connected therewith respectively, a plug cover connected to the main body and a plug union threadably mounted around said plug cover for meshing engagement with the tapped sleeve of said mount of the socket are enclosed by a cover, with cord socket. connecting portions of the terminal plates only project- 2. A switch-incorporated plug socket according to ing outwardly from said cover. claim 1, in which the component parts provided on the 

1. A switcH-incorporated plug socket comprising a socket having a main body provided with a tapped sleeve, a mount of electrically insulating material fixed to the main body on the opposite side to said tapped sleeve, a plurality of plug receiving members fixed to one end of said mount within said tapped sleeve and respectively opening in the same direction as the direction in which said tapped sleeve is open, metal strips fixed on said mount and electrically connected with said plug receiving members respectively, terminal plates fixed on said mount at locations opposite to said metal strips respectively, a guide rod slidably extending through the center of said mount in parallel to the plug receiving members with one end thereof protruding into said tapped sleeve, said guide rod being enlarged in diameter at the central portion thereof and formed with an annular groove at said enlarged diameter portion perpendicular to the axis thereof, side plates fixed in opposed relation to the opposite side walls of said mount parallel to said metal strips and terminal plates with portions thereof projecting above said mount, a pressing plate of electrically insulating material disposed horizontally with the opposite ends thereof respectively received in openings formed in said side plates, said pressing plate being provided at the central portion with an opening in which said guide rod is extended, contactor strips fixed to the opposite end portions of said pressing plate and adapted to be brought into contact concurrently with said metal strips and terminal plates, means for urging said guide rod constantly towards the tapped sleeve, and leaf springs mounted between the opposite end portions of the pressing plate and the annular groove of the guide rod and adapted to move the pressing plate away from the mount when the guide rod is moved towards the tapped sleeve and to move the same towards the mount when the guide rod is moved in the opposite direction to the tapped sleeve; and a plug having a main body adapted to be inserted into the tapped sleeve of said socket, plugs provided on the main body and adapted to be received in the plug receiving members of said socket respectively, terminals provided on the main body on the opposite side to said plugs and electrically connected therewith respectively, a plug cover connected to the main body and a plug union threadably mounted around said plug cover for meshing engagement with the tapped sleeve of said socket.
 2. A switch-incorporated plug socket according to claim 1, in which the component parts provided on the mount of the socket are enclosed by a cover, with cord connecting portions of the terminal plates only projecting outwardly from said cover. 